EnhanceModule

This gem adds a typed, sorbet-friendly way of extending object instances with modules.

Install the gem and add to the application's Gemfile by executing:

$ bundle add enhance_module

If bundler is not being used to manage dependencies, install the gem by executing:

$ gem install enhance_module

Ruby supports extending objects with methods from modules. It's one of the most unique and cool features of Ruby.

module Foo
    def foo = "foo!"
end

obj = Object.new
obj.extend(Foo)
obj.foo #=> foo!

Unfortunately sorbet does not support this feature. Its type system in unable to fathom what is going on when an object is extended.

# typed: true

module Foo
    extend T::Sig

    sig { void }
    def foo = "foo!"
end

obj = Object.new
obj.extend(Foo)
obj.foo #! Method `foo` does not exist on `Object`

This gem adds a new sorbet-friendly way of extending objects.

# typed: true

require 'enhance_module'

module Foo
    extend T::Sig

    # boilerplate that needs to be added
    # to your module to make it support
    # extending objects
    class << self
        extend T::Sig
        include EnhanceModule
        has_attached_class! { { fixed: Foo } }
    end

    # define your methods
    sig { void }
    def foo = "foo!"
end

obj = Object.new
# works the same as `obj.extend(Foo)`
# but sorbet understands it
extended_obj = Foo.enhance(obj)
extended_obj.foo # ok!

T.reveal_type(extended_obj) # T.all(Foo, Object)

The new Foo.enhance method works like extend and returns an intersection type that consists of the argument's class and the module that is being extended.

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/Verseth/enhance_module.

The gem is available as open source under the terms of the MIT License.